Browsing by Author "Jegga, Anil G."

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    Association of Baseline Luminal Narrowing With Ileal Microbial Shifts and Gene Expression Programs and Subsequent Transmural Healing in Pediatric Crohn Disease
    (Oxford University Press, 2021) Ta, Allison D.; Ollberding, Nicholas J.; Karns, Rebekah; Haberman, Yael; Alazraki, Adina L.; Hercules, David; Baldassano, Robert; Markowitz, James; Heyman, Melvin B.; Kim, Sandra; Kirschner, Barbara; Shapiro, Jason M.; Noe, Joshua; Oliva-Hemker, Maria; Otley, Anthony; Pfefferkorn, Marian; Kellermayer, Richard; Snapper, Scott; Rabizadeh, Shervin; Xavier, Ramnik; Dubinsky, Marla; Hyams, Jeffrey; Kugathasan, Subra; Jegga, Anil G.; Dillman, Jonathan R.; Denson, Lee A.; Pediatrics, School of Medicine
    Background: Transmural healing (TH) is associated with better long-term outcomes in Crohn disease (CD), whereas pretreatment ileal gene signatures encoding myeloid inflammatory responses and extracellular matrix production are associated with stricturing. We aimed to develop a predictive model for ileal TH and to identify ileal genes and microbes associated with baseline luminal narrowing (LN), a precursor to strictures. Materials and methods: Baseline small bowel imaging obtained in the RISK pediatric CD cohort study was graded for LN. Ileal gene expression was determined by RNASeq, and the ileal microbial community composition was characterized using 16S rRNA amplicon sequencing. Clinical, demographic, radiologic, and genomic variables were tested for association with baseline LN and future TH. Results: After controlling for ileal location, baseline ileal LN (odds ratio [OR], 0.3; 95% confidence interval [CI], 0.1-0.8), increasing serum albumin (OR, 4; 95% CI, 1.3-12.3), and anti-Saccharomyces cerevisiae antibodies IgG serology (OR, 0.97; 95% CI, 0.95-1) were associated with subsequent TH. A multivariable regression model including these factors had excellent discriminant power for TH (area under the curve, 0.86; positive predictive value, 80%; negative predictive value, 87%). Patients with baseline LN exhibited increased Enterobacteriaceae and inflammatory and extracellular matrix gene signatures, coupled with reduced levels of butyrate-producing commensals and a respiratory electron transport gene signature. Taxa including Lachnospiraceae and the genus Roseburia were associated with increased respiratory and decreased inflammatory gene signatures, and Aggregatibacter and Blautia bacteria were associated with reduced extracellular matrix gene expression. Conclusions: Pediatric patients with CD with LN at diagnosis are less likely to achieve TH. The association between specific microbiota, wound healing gene programs, and LN may suggest future therapeutic targets.
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    Chromatin-associated APC regulates gene expression in collaboration with canonical WNT signaling and AP-1
    (Impact Journals, 2018-07-27) Hankey, William; Chen, Zhong; Bergman, Maxwell J.; Fernandez, Max O.; Hancioglu, Baris; Lan, Xun; Jegga, Anil G.; Zhang, Jie; Jin, Victor X.; Aronow, Bruce J.; Wang, Qianben; Groden, Joanna; Medical and Molecular Genetics, School of Medicine
    Mutation of the APC gene occurs in a high percentage of colorectal tumors and is a central event driving tumor initiation in the large intestine. The APC protein performs multiple tumor suppressor functions including negative regulation of the canonical WNT signaling pathway by both cytoplasmic and nuclear mechanisms. Published reports that APC interacts with β-catenin in the chromatin fraction to repress WNT-activated targets have raised the possibility that chromatin-associated APC participates more broadly in mechanisms of transcriptional control. This screening study has used chromatin immunoprecipitation and next-generation sequencing to identify APC-associated genomic regions in colon cancer cell lines. Initial target selection was performed by comparison and statistical analysis of 3,985 genomic regions associated with the APC protein to whole transcriptome sequencing data from APC-deficient and APC-wild-type colon cancer cells, and two types of murine colon adenomas characterized by activated Wnt signaling. 289 transcripts altered in expression following APC loss in human cells were linked to APC-associated genomic regions. High-confidence targets additionally validated in mouse adenomas included 16 increased and 9 decreased in expression following APC loss, indicating that chromatin-associated APC may antagonize canonical WNT signaling at both WNT-activated and WNT-repressed targets. Motif analysis and comparison to ChIP-seq datasets for other transcription factors identified a prevalence of binding sites for the TCF7L2 and AP-1 transcription factors in APC-associated genomic regions. Our results indicate that canonical WNT signaling can collaborate with or antagonize the AP-1 transcription factor to fine-tune the expression of shared target genes in the colorectal epithelium. Future therapeutic strategies for APC-deficient colorectal cancers might be expanded to include agents targeting the AP-1 pathway.
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    Exome Sequencing Identifies Candidate Genetic Modifiers of Syndromic and Familial Thoracic Aortic Aneurysm Severity
    (Springer Nature, 2017-08) Landis, Benjamin J.; Schubert, Jeffrey A.; Lai, Dongbing; Jegga, Anil G.; Shikany, Amy R.; Foroud, Tatiana; Ware, Stephanie M.; Hinton, Robert B.; Pediatrics, School of Medicine
    Thoracic aortic aneurysm (TAA) is a genetic disease predisposing to aortic dissection. It is important to identify the genetic modifiers controlling penetrance and expressivity to improve clinical prognostication. Exome sequencing was performed in 27 subjects with syndromic or familial TAA presenting with extreme phenotypes (15 with severe TAA; 12 with mild or absent TAA). Family-based analysis of a subset of the cohort identified variants, genes, and pathways segregating with TAA severity among three families. A rare missense variant in ADCK4 (p.Arg63Trp) segregated with mild TAA in each family. Genes and pathways identified in families were further investigated in the entire cohort using the optimal unified sequence kernel association test, finding significance for the gene COL15A1 (p = 0.025) and the retina homeostasis pathway (p = 0.035). Thus, we identified candidate genetic modifiers of TAA severity by exome-based study of extreme phenotypes, which may lead to improved risk stratification and development of new medical therapies.
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    Mucosal Inflammatory and Wound Healing Gene Programmes Reveal Targets for Stricturing Behaviour in Paediatric Crohn’s Disease
    (Oxford University Press, 2020-08-08) Haberman, Yael; Minar, Phillip; Karns, Rebekah; Dexheimer, Phillip J.; Ghandikota, Sudhir; Tegge, Samuel; Shapiro, Daniel; Shuler, Brianne; Venkateswaran, Suresh; Braun, Tzipi; Ta, Allison; Walters, Thomas D.; Baldassano, Robert N.; Noe, Joshua D.; Rosh, Joel; Markowitz, James; Dotson, Jennifer L.; Mack, David R.; Kellermayer, Richard; Griffiths, Anne M.; Heyman, Melvin B.; Baker, Susan S.; Moulton, Dedrick; Patel, Ashish S.; Gulati, Ajay S.; Steiner, Steven J.; LeLeiko, Neal; Otley, Anthony; Oliva-Hemker, Maria; Ziring, David; Gokhale, Ranjana; Kim, Sandra; Guthery, Stephen L.; Cohen, Stanley A.; Snapper, Scott; Aronow, Bruce J.; Stephens, Michael; Gibson, Greg; Dillman, Jonathan R.; Dubinsky, Marla; Hyams, Jeffrey S.; Kugathasan, Subra; Jegga, Anil G.; Denson, Lee A.; Pediatrics, School of Medicine
    Background and aims: Ileal strictures are the major indication for resective surgery in Crohn's disease (CD). We aimed to define ileal gene programs present at diagnosis linked with future stricturing behavior during five year follow-up, and to identify potential small molecules to reverse these gene signatures. Methods: Antimicrobial serologies and pre-treatment ileal gene expression were assessed in a representative subset of 249 CD patients within the RISK multicenter pediatric CD inception cohort study, including 113 that are unique to this report. These data were used to define genes associated with stricturing behavior and for model testing to predict stricturing behavior. A bioinformatics approach to define small molecules which may reverse the stricturing gene signature was applied. Results: 19 of the 249 patients developed isolated B2 stricturing behavior during follow-up, while 218 remained B1 inflammatory. Using deeper RNA sequencing than in our prior report, we have now defined an inflammatory gene signature including an oncostatin M co-expression signature, tightly associated with extra-cellular matrix (ECM) gene expression in those who developed stricturing complications. We further computationally prioritize small molecules targeting macrophage and fibroblast activation and angiogenesis which may reverse the stricturing gene signature. A model containing ASCA and CBir1 serologies and a refined eight ECM gene set was significantly associated with stricturing development by year five after diagnosis (AUC (95th CI) = 0.82 (0.7-0.94)). Conclusion: An ileal gene program for macrophage and fibroblast activation is linked to stricturing complications in treatment naïve pediatric CD, and may inform novel small molecule therapeutic approaches.